The present invention generally relates to cooling of the exhaust section of a gas turbine, and, particularly, relates to cooling of the struts on a gas turbine inner casing in an exhaust section.
A gas turbine engine combusts a mixture of fuel and compressed air to generate hot combustion gases, which drives turbine blades to rotate a shaft in the exhaust section supported by bearings and casings. The rotation of the shaft may generate significant amounts of heat in the turbine. Also, the hot turbine exhaust gases flowing through an exhaust section may transfer heat to the exhaust casings in the exhaust section.
An inner casing in an exhaust section of a gas turbine is heated by the exhaust gas from the turbine engine. The inner casing may also experience thermal heating due to friction from the shaft in the casing. Inner casing in a turbine exhaust component may not be adequately and uniformly cooled due to differences in body mass throughout the inner casing, such as the flanges at the split line and at the roots of the struts connected to the inner casing. Uneven cooling of the struts may cause differences in thermal contraction and expansion in different areas of the inner casing, and induce damages associated with thermal stress.
Methods of cooling turbine exhaust casing components have been described using a flow of cooling fluids (e.g. ambient air) through the exhaust section. Cooling systems are disclosed in U.S. Pat. Nos. 7,493,769; 6,578,363; 7,373,773; 2013/0064647; and 2013/0084172.